The present invention relates to a working apparatus for a crankshaft used in a car engine, and more particularly, to a working apparatus for a crankshaft, adapted to work those portions of the crankshaft which are subject to stress concentration.
Engine crankshafts generally comprise journal portions, crank arms, and crank pins. When a crankshaft rotates, stress concentrates on those corner portions of the journal portions and crank pins which adjoin the crank arms. Accordingly, these corner portions are work-hardened to be improved in mechanical strength by means of a working apparatus.
The working apparatus of this type comprises receiving rollers, used to support the crankshaft, and fillet rollers, which are pressed against the corner portions of the journal portions and the crank pins by means of a drive mechanism. The fillet rollers are rotated by rotating the crankshaft supported by the receiving rollers. In this manner, the corner portions are work-hardened.
In the prior art working apparatus, however, the pressure applied to the corner portions by the fillet rollers can be detected simply as a load by means of load cells and the like. Thus, the corner portions cannot enjoy a constant pressure, so that the worked crankshaft is subject to variation in hardness and therefore, is low in reliability.